The present invention relates to a gate or door closing hinge comprising a first hinge part, a second hinge part, a hinge shaft rotatably mounted about a first rotation axis in the first hinge part and connecting the first hinge part to the second hinge part, a torsion spring having a longitudinal axis coinciding substantially with said first rotation axis and having a first end fixed with respect to the first hinge part and a second end fixed with respect to the hinge shaft to exert a door or gate closing moment onto the first hinge part, and means for adjusting the moment exerted by the torsion spring on the first hinge part.
Hinges comprising a torsion spring for closing the door or gate against which they are mounted are known. When assembling the hinges, the torsion spring is pre-tensioned so that the door or gate has to be opened against a predetermined spring tension. In practice, there exist moreover systems for adjusting the tension of the torsion spring when the hinges are already mounted on the door or gate. An example of such a system are the TRU-CLOSE® adjustable self-closing gate hinges which are available on the market.
The TRU-CLOSE® adjustable self-closing gate hinges are mounted in the same way as conventional hinges on the outside of the gate and the pole. The torsion spring is arranged within the hinge, around the hinge shaft. The hinge shaft has a hexagonal head which fits in a cavity in the second hinge part. By means of a screwdriver, the hexagonal head can be depressed against the action of the helical torsion spring and rotated to adjust the tension of the torsion spring. In this way a quite compact adjusting system is achieved. A drawback of such an adjustment system is however that, when depressing the head of the hinge shaft, the screwdriver has to be held very strongly and a large force has to be exerted thereon in order to be able to increase the tension of the torsion spring. Indeed, when depressing the hexagonal head, the entire tension of the torsion spring acts upon the screwdriver.